1. Field of the Invention
This invention relates to ball-point pens and, more particularly, to a ball-point pen having a ball socket with a ball seat comprising a plurality of convex surfaces.
2. Description of the Prior Art
Prior art ball-point pens include a ball holder comprising a ball holder body with a hollow interior for containing an ink source, a ball socket formed at a tip of the body with a crimped rim to retain a ball within the socket, a ball seat disposed within the body inwardly or communicatively with the ball socket, and an ink feed system extending from the ball seat to the hollow interior of the body for supplying ink to a surface of the ball. It is desirable to arrange the ink feed system to provide a flow of ink which would adhere uniformly to the ball surface so that the ball would provide a uniform ink laydown when rotated across a writing surface. A type of known ink feed system having a plurality of narrow capillary channels with a star-shaped cross section is particularly suitable for supplying ink to the ball. However, the narrow capillary channels are susceptible to clogging by foreign matter which sometimes infiltrate into the ball socket. A clogged channel obstructs the flow of ink to the ball causing a non-uniform ink coating on the ball surface resulting in writing irregularities, such as skipping or thinning of written lines.
Prior art ball holders are arranged to minimize skipping or thinning of written lines by extending a relatively large diameter ink feed port between the hollow interior of the body and the ball seat. In addition, concavities are formed between the ball and recesses in the ball seat. The concavities are arranged to collect ink, and supply the same uniformly, and in ample quantity, to the entire surface of the ball. Narrow grooves or capillary channels are formed at corners of the ink feed port for supplying ink by capillary action to the concavities, so that a constant quantity of ink is always stored in the concavities, while excessive feeding of ink is avoided and dripping of ink and blotching are prevented. An example of a ball holder with a ball seat including a plurality of substantially flat contact surfaces oriented to form tangent planes to the writing ball and a peripheral succession of shallow ink channels around the ball is disclosed in U.S. Pat. No. 3,703,234.
The known ball-point pens using the previously described ball holder are subject to writing irregularities when the act of writing causes the ball to eventually wear into the ball seat and the ink collecting concavities to disappear. Accordingly, it is desired to arrange a ball holder with a ball seat forming ink collecting concavities which would continue to collect and supply ink to the ball surface despite ball seat wear over the writing life of the ball-point pen.